Thailand has seen two coups, three prime ministers brought down by court rulings, intermittent violence and crippling colour-coded street demonstrations during two decades of political instability.
Below are key events leading up to Sunday's election.
2001 - Billionaire telecommunications tycoon Thaksin Shinawatra is elected prime minister on a populist platform. He is hugely popular, widely regarded as a mould-breaking premier who oversaw economic growth, prioritised the rural poor and courted foreign investors with plans for modernisation.
2005 - Thaksin's Thai Rak Thai Party wins another election in a landslide, the first Thai party to win re-election.
2006 - Allegations of Thaksin's corruption, cronyism, neptotism and abuse of power take hold, worsened by the tax-free sale of his family's Shin Corporation to Singapore state investor Temasek for 73 billion baht ($2.16 billion). His enemies orchestrate massive demonstrations against him, donning yellow shirts, the colour of the monarchy, and accusing him of disloyalty to the king. Thaksin denies wrongdoing.
The royalist military ousts Thaksin while he is in New York and he takes temporary refuge in Britain. Thai Rak Thai is dissolved for violating election law and Thaksin and party executives are banned from politics for five years.
2007 - Thai Rak Thai is re-launched as the People Power Party (PPP) and wins an election. Former Bangkok governor Samak Sundaravej becomes prime minister.
2008 - Thaksin returns to Thailand in February. Samak is disqualified as premier for appearing in a TV cooking show and Thaksin's brother-in-law, Somchai Wongsawat, takes over as prime minister.
Yellow Shirts seize Bangkok's two international airports for 10 days and the blockade ends when a court dissolves PPP for electoral fraud. The Pheu Thai Party is created in its place.
A new coalition government is formed with the opposition Democrat Party at the helm. Thaksin leaves Thailand into self-imposed exile before a court convicts him of a conflict of interest and sentences him to two years in prison.
2009 - A "red shirt" movement of Thaksin's mostly rural supporters hold weeks of rallies in Bangkok against the Democrat-led government, calling it unelected and illegitimate.
Red shirts storm an international summit in the seaside town of Pattaya, forcing leaders of China, Japan and Southeast Asian countries to flee. In Bangkok, rioting and arson ensues after confrontations between demonstrators and the military.
2010 - Red shirt protests resume and demonstrators set up camp in Bangkok's commercial heart for 10 weeks, paralysing business. Army efforts to disperse the protests turn deadly on several occasions, with more than 90 people killed, mostly protesters, the worst political violence in nearly two decades.
2011 - Pheu Thai wins an election in a landslide. Thaksin's popular but politically inexperience sister, Yingluck Shinawatra, becomes prime minister.
2013 - Anti-government protests resume in Bangkok after Yingluck's government introduces an amnesty bill that could have led to Thaksin’s return. The bill fails but the protests go on for months. Yingluck calls a snap election.
2014 - Elections are held but invalidated due to disruption. Protests intensify, the seat of government is breached but Yingluck's government stands firm. Martial law is declared to prevent bloodshed.
Yingluck steps down after a court finds her guilty of abuse of power. The military calls a meeting between the government and protesters to chart a way out of the crisis, during which army chief Prayuth Chan-ocha announces the talks have failed and the military is taking power in a coup.
2016 - King Bhumibol Adulyadej dies after a 70-year reign. He is succeeded by his son, King Maha Vajiralongkorn.
2017 - Yingluck flees Thailand ahead of a verdict against her over her government's rice subsidy scheme and jail term of five years. A military-drafted constitution is approved in a referendum.
2019 - Elections are held, Prayuth's army-backed Palang Pracharat party wins fewer seats than Pheu Thai but forms the government, with Pheu Thai in opposition. Prayuth is elected prime minister in a vote by the lower house and the junta-appointed Senate. Opposition parties say the process was rigged, which Prayuth denies.
2020 - A court dissolves the opposition Future Forward Party. Its billionaire founder Thanathorn Juangroongruangkit is banned from politics. Student-led protests begin and for the first time demand reform of the monarchy.
2021 - Protests die down as COVID-19 restrictions intensify. Legal cases against protest leaders mount.
2023 - Prayuth calls an election for May 14. Thaksin's daughter, Paetongtarn Shinawatra is named a Pheu Thai candidate for prime minister.
Just a few days away from the election, Thaksin says he is seeking to end his 17 years in exiled and return.
(Compiled by Chayut Setboonsarng; Editing by Martin Petty, Robert Birsel)
